Apparatus and method for false twisting yarns



June 4, 1963 G. A. CARRUTHERS 3,091,908

APPARATUS AND METHOD FOR FALSE TWISTING YARNS Filed May 21, 1962 4 Sheets-Sheet l BY @JaGP-J June 4, 1963 3,091,908

APPARATUS AND METHOD FOR FALSE TWISTING YARNS G. A. CARRUTHERS 4 Sheets-Sheet 2 Filed May 21, 1962 I INVENTOR. 'mzyeJ. (Zrrazfigra,

62d: @JZ

ATTORNEYS.

June 1963 G. A. CARRUTHERS 3,091,903

APPARATUS AND METHOD FOR FALSE TWISTING YARNS Filed May 21, 1962 4 Sheets-Sheet 3 1 181 5 FIG. 8

INVENTOR BY @J: @J

4 rraems'xs,

June 1963 G. A. CARRUTHERS 3,0

APPARATUS AND METHOD FOR FALSE TWISTING YARNS Filed May 21, 1962 4 Sheets-Sheet 4 FIG. 9

INVENTOR. film/ye J. (arr/likens,

QJsG MQ A TTOBIVEYS- United States Patent Ofiice 3,691,908 Patented June 4, 1963 3,691,968 APPARATUS AND METHQD FUR FALSE TWISTKNG YARNS George Alan Cari-others, Harieysville, Pa, assignor to Turbo Machine Company, Lansdale, Pin, a corporation of Pennsylvania Filed May 21, 1962, Ser. No. 195,270 Claims. (Si. 57-34) This invention relates to an apparatus and method for modifying synthetic heat-set-table yarn filaments. More specifically, the invention relates to the false twisting of yarn composed of synthetic material which is subject to heat-setting, but difiers sharply from most conventionfl false twisting apparatus and methods which require a spindle which rotates at high speed.

False twist yarn has conventionally been produced at speeds of about meters per minute, utilizing false twist spindles. Although strong efforts have been made in the art for years to increase the linear velocity of the yarn, such efforts have heretofore been unsuccessful in view of the inherent limitations as to speed of rotation of the false twist spindle.

It is an object of this invention to provide a new apparatus and method for producing false twist type yarn with drastically increased speed. Another object is to provide an apparatus and method for producing false twist type yarn having radically improved uniformity. Other objects and advantages of this invention will further appear and in the drawings whereof:

FIG. 1 represents a top plan View showing one specific form of apparatus having utility in carrying this invention into effect.

FIG. 2 is a sectional view taken as indicated by the lines and arrows 11-11 which appear in FIG. 1.

FIG. 3 is a fragmentary view in side elevation showing portions of the apparatus appearing in FIG. 1.

FIG. 4 is a top plan view showing a portion of the apparatus appearing in FIG. 1, with yarn withdrawing means shown in a modified position.

FIGS. 5, 6 and 7 are fragmentary top plan views illustrating the operation of the yarn withdrawal means.

FIG. 8 is a fragmentary top plan view showing a modified form of method in accordance with this invention.

FIG. 9 is a schematic top plan view showing a modified form of apparatus and method using a dummy end, and

FIG. 10 is an enlarged View of a portion of the twisted ends shown in FIG. 9.

The drawings and the following description of the rawings are intentionally directed to specific embodiments of the invention and ar not intended to limit the scope of the patent, such being defined by the appended claims. Referring specifically to FIGS. 1-3 of the drawings, frame it) carries pairs of spaced apart feed rolls lit for feeding separate ends of yarn Y from pirns 12, in the direction indicated by the arrows. Each yarn passes through a guide 13 and is turned repeatedly around the upper roll 11, emerging from the nip between the upper and lower rolls ll.

The number 14 designates separating pins for the yarns, which converge and which are pro-twisted to form a twisted zone T extending along a predetermined longitudinal axis. The yarns, which diverge from one another at a point of separation S, are shown in FIG. 1 as being directed to opposite sides of the longitudinal axis of the twisted zone, each passing through the nip between an upper conical roll 15 and a lower conical roll 16 (see particularly FIG. 2). Preferably, though not necessarily, upper roll 15' is rubber and lower roll 16 is metal. As shown, the large diameter of each conical roll is twice the small diameter and this may be varied to suit specific conditions. Upper loll 15 is mounted on shaft 17, pivoted at 20 to a support 21 which in turn is pivoted at 22 to the frame 10. Upper roll 15 is springurged downwardly toward lower roll 16' by a spring 23.

Means are provided for driving the feed rolls 11 and the conical rolls 16. This drive means includes a motor 24, belt 25 and sprocket 26 which is secured on the lower feed roll shaft 27. At the opposite end of shaft 27 is a bevel gear 35 meshing with a shaft gear 31 fixed on shaft 32 which at its opposite end drives a belt 33 conected through gears 34, 35 to flexible drive shafts 36 drivingly connected to the lower conical rolls 16. Thus, the conical withdrawal rolls 15, in are driven in timed relation with respect to the feed rolls 11, in a manner to maintain the yarn suspended between such sets of rolls, under a limited and predeterminable amount of tension. Preferably, the peripheral speeds at approximately the longitudinal centers of the conical rolls are equal to the peripheral speeds of the feed rolls.

Means are provided for heating the yarn in a twisted condition. This means as shown in the drawings is a hot plate 37 energized by wires 40 and provided with a temperature indicator 41. As shown in FIG. 3, hot plate 37 is curved upwardly at its upstream end, whereby the twisted yarns contact its upper surface in a generally tangential manner. The upstream portion of the twisted yarns is in pressure contact against the top surface of hot plate 37. Thus, the twisted yarns are subjected to heat at a temperature which is sulhcient to heatset the yarns in a twisted condition.

Optional means are provided for cooling the yarn. Such means include an air pipe 42 having a nozzle 43 for directing a stream of cold air upon the twisted yarns after such yarns leave the hot plate 37. Since ambient conditions in the mill are frequently suflicient, a shut-off valve 44 is provided for the air.

In operation, the apparatus is set up by arranging each yarn for separate feed, so that nips are provided keeping the yarns separate, then by arranging the yarns around outwardly of the separating pins 14, and then the yarns are pro-twisted by the operator, utilizing any desired number of turns in either desired direction, i.e. clockwise or counterclockwise. The yarns are then placed at random in the nip between the conical rolls l5, l6, and slight tension is exerted. With the hot plate heated to its heatsetting temperature, the twisted yarns should be kept away from the hot plate so long as such yarns are stationary, but the machine can be started up by energizing the motor 24 and immediately allowing the twisted yarns to contact the upper surface of hot plate 37.

It is known that many yarns shrink when heated, and shrinkage of the twisted yarns during the start-up period is readily compensated for by automatic adjustments of the yarn withdrawal rate, as will further become apparent hereinafter.

It will be appreciated that, as the apparatus is operated at exceedingly high speed, slight variations of friction, as well as slight vibrations and the like, tend to cause a wandering of the point of separation S, since the yarn is substantially suspended under tension between the feed rolls and the withdrawal rolls. Notwithstanding efforts to the contrary, the normal tendency is for one of the yarns withdrawn to be withdrawn momentarily somewhat faster than the other, thus drawing the point of separation S of: to one side or the other of the normal axis of the twisted yarn, ultimately catching both withdrawn yarns in the nip of the same rolls, causing a time-consuming and costly shut-down and also damaging substantial quantities of yarn. This disadvantage is automatically overcome in accordance with this invention, as is illus trated more particularly in 'FIGS. 5, 6 and 7.

Referring now to FIGS. 5, 6 and 7 specifically, it will be appreciated that the yarn being withdrawn from the point S is normally drawn straight out and has only a very slightly wavy appearance. Such appearance, however, has been greatly magnified in these figures for clarity of illustration of the relative tension differences which control the automatic operation of the yarn withdrawal means. FIG. shows schematically a steady state condition wherein the point of separation S is exactly centered between the two conical take-off rolls. If the withdrawal rates become unbalanced or if any other factors tend to cause the point of separation S to move toward the left as shown in FIG. 6, the left hand yarn is automatically displaced axially along the left hand conical roll, thus becoming contacted by a peripheral portion of less diameter, thusslowing down the linear speed of the withdrawal of that yarn. At the same time, the right hand yarn moves axially toward a large diameter portion 7 of its conical roll, thus increasing the linear rate of withdrawal. This draws the point of separation automatically and immediately to the right.

FIG. 7 shows the opposite situation, where in the point of separation S is withdraw to the right, at which time the right hand yarn is automatically slowed down and the left hand yarn is automatically sped up. In this manner, the point of separation S moves back and forth, seeking and quickly finding its central point as illustrated in FIG. 5, thus automatically compensating for any difference of yarn tension as between the left hand and the right hand yarns being withdrawn. This is an important and ad 'vantageous feature of this invention.

FIG. 4 shows how the conical rolls can be pivoted toward and away from one another in order to regulate the total tension on the twisted yarns in the twisted zone T. As shown in FIG. 4, the conical rolls are pivoted quite far toward one another, providing a situation where a greatly reduced tension is present in the twisted yarns.

FIG. 8 shows a modification of the invention wherein the two left hand yarns are twisted together with a counter-clockwise twist (sometimes referred to as S twist) whereas the two right hand yarns are twisted together with a clockwise twist (Z twist). After passing over the hot plate 37 and after being cooled by subjecting to ambient conditions in the area C, the yarns are separated 'by withdrawing one of the S twist yarns to the left and one of the Z twist yarns to the left, thus doubling an S and a Z twist yarn, providing a yarn which the trade refers to as a balanced yarn. Similarly, a Z twist yarn and an S twist yarn we Withdrawn toward the right, providing another balanced yarn. Thus, in this manner, the invention can be utilized extremely eifectively to provide balanced yarns.

Accordingly it will be appreciated that this invention provides automatic adjustment of yarn position at the withdrawal point, which is exceedingly important especially when high speeds as high as 1000 meters per minute are attained. This enables the attainment of speeds which are vastly in excess of those obtained when using false twist spindles, which are usually on the order of meters per minute. Of course, the extremely high rate of productivity particularly when commensurate with far better uniformity, produces yarn at much less cost, which yarn nevertheless has superior quality. Additionally, all of the other drawbacks associated with the use of spindles, such as maintenance and the like, are eliminated.

It is of particular advantage that variations in tension at the withdrawal area are immediately compensated for not only by speeding up or slowing down one yarn, but

by concurrently speeding up one yarn and slowing down the other. This provides an immediately effective correction-of tension differences.

7 It is of further importance and significance that this invention is fully operative even when diiferent yarns are .twisted together. One may be polyester for example and dthe other nylon, or the yarns can be of different denie1- without adversely affecting the operation of the invention.

As shown in FIGS. 9 and 10, one of the yarns may be a dummy yarn D which is simply recirculated in a closed loop around pulleys 5i never drawn ofif as prodnot. This may even be so much thicker 0r stronger that it forms'a substantially straight-line core about which the other yarn is helically wound, see FIG. 10. This produces a special torqued form of filament modificationa torqued product having special value.

It will be appreciated that this invention is applicable to the filament modification of textile fibers generally, whether in the form of continuous filaments or of spun yarns, whether the continuous product incorporating the filaments is of a weight suitable for use directly as a yarn or isof substantially greater weight such as that of tow for example, which is intended for subsequent cutting or chopping into staple fibers, for subsequent conversion into a yarn. The best crimp is often obtained, however, when the ends are mutually twisted when they are in the heat-setting zone, as distinguished from heating them prior to twisting.

It will be appreciated further that the invention is applicable to the twisting of more than two yarns together, and to the use of doubled yarns or yarns in multiple, twisted as a unit with respect to another doubled or multiple yarn.

It is of particular importance that the filaments must be those which are thermoplastic and therefore subject to heat-setting, by which is meant the application of heat in a manner to achieve a permanent set in the filaments. Various thermoplastic filaments are susceptible of heatsetting and are ideally treated in accordance with this invention. Particular examples are filaments of nylon (polyhexamethylene adipamide), polyaminocaproic acid, and polyethylene terephthalate (Dacron), for example. Other examples, such as co-polymers of vinylidene chloride and vinyl chloride known as saran and substances such as polypropylenes for example, are also subject to heat-setting and many others having this property are included within the scope of this invention.

Although a heated plate has been shown, other heating means such as elongated tubes and the like (for example) may be substituted. Further, special cooling means such as cooling tubes may be used in association with any such heating means.

While this invention has been described with reference to specific embodiments thereof, it will be apparent to those skilled in the art that various changes other than those referred to above may be made in the form of the device, that equivalent elements may be substituted for those illustrated in the drawings, that parts may be reversed, and that certain features of the invention may be used to advantage independently of the use of other features, all within the spirit and scope of the invention as defined in the appended claims.

The following is claimed:

1. In a method of modifying thermoplastic heat-settable yarn filaments the steps which comprise pre-twisting a plurality of ends of said yarns together, tensioningthem, passing them while twisted through a heating zone maintained at a heat-setting temperature, cooling the heat-set yarns in a twisted, tensioned condition, separating the ends of yarn continuously from one another by withdrawing said yarns in different directions, and automatically varying the rate of withdrawal of each yarn thereby maintaining substantially constant tension on the twisted yarns.

2. In a method of modifying thermoplastic heat-settable yarn filaments the steps which comprise pre-twisting stantially equal rates in difierent directions thereby establishing a floating point of separation, and automatically controlling the rate of withdrawal of each yarn from said point thereby maintaining said floating point of separation substantially stationary, by automatically increasing the rate of withdrawal of either end of yarn whenever the tension in said yarn decreases and automatically decreasing said rate whenever said tension increases.

3. In a method of modifying thermoplastic heat-settable yarn filaments the steps which comprise twisting together a plurality of continuously advancing ends of said yarns arranged along a predetermined longitudinal axis, tensioning said yarns along said axis, passing them while twisted through a heating zone maintained at a heat-setting temperature along said axis, cooling the heat-set yarns in a twisted, tensioned condition, separating the ends of yarn continuously from one another by withdrawing said yarns in difierent directions on opposite sides of said axis, and automatically controlling the rate of withdrawal of each yarn in response to difierences of withdrawal tension on one side relative to the other, thereby maintaining substantially constant tension on the twisted yarns.

4. In a method of modifying thermoplastic heat-settable yarn filaments the steps which comprise twisting a plurality of ends of said yarns together, tensioning them, passing them while twisted through a heating zone maintained at a heat-setting temperature, cooling the heat-set yarns in a twisted, tensioned condition, separating the ends of yarn continuously from one another by withdrawing said yarns in different directions, and automatically controlling the rate of withdrawal of each yarn in response to differences of tension as between said withdrawn yarns by increasing the rate of withdrawal of one yarn and concurrently decreasing the rate of withdrawal of the other until said tensions are substantially bflanced.

5. In a method of modifying thermoplastic heat-settable yarn filaments the steps which comprise twisting two ends of yarn together forming a twisted length with untwisted extensions, gripping said extensions of one end of yarn at two longitudinally spaced feed and withdrawal points, grippingsaid extensions of the other end of yarn at two longitudinally spaced feed and withdrawal points which are adjacent to the first mentioned points, tensioning them, continuously feeding said yarns while thus gripped and twisted and passing them through a heating zone maintained at a heat-setting temperature, cooling the heat-set yarns in a twisted, tensioned condition, separating the ends of yarn continuously from one another by withdrawing said yarns in different directions at said withdrawal points, automatically sensing any decrease of tension of either yarn and increasing its rate of withdrawal in response to such decrease of its tension, and concurrently decreasing the rate of withdrawal of the other yarn until the respective tensions are balanced.

6. In a method of making balanced false twist thermoplastic heat-settable yarn, each such yarn containing an end having clockwise twist and another end having counter-clockwise twist, the steps which comprise pre-twisting a pair of ends of said yarns together in a clockwise direction, pre-twisting another pair of ends of said yarns together in a counter-clockwise direction, tensioning the clockwise and counter-clockwise pre-twisted yarns in substantially parallel relation along an axis, passing them concurrently through a heating zone maintained at a heatsetting temperature, cooling the heat-set yarns in a tensioned condition, separating the ends of yarn continuously from one another by withdrawing said yarns in difierent directions, one end from the clockwise pre-twist and one from the counter-clockwise pre-twist to one side of said axis and the others to the opposite side of said axis, and automatically controlling the rate of withdrawal of each such doubled balanced yarn thereby maintaining substantially constant tension on the yarns.

7. Apparatus for modifying heat-settable yarn filaments comprising means for feeding a plurality of pre-twisted yarns in a tensioned condition continuously through a heat-setting zone, withdrawal means for drawing said yarns, after heat-setting, apart from one another and automatically responsive to a decrease of tension in a yarn being withdrawn for increasing the rate of withdrawal of that yarn and for decreasing the rate of withdrawal of the other thereby equalizing the tensions of the yarns withdrawn.

8. Apparatus for modifying heat-settable yarn filaments comprising means for feeding a plurality of pretwisted yarns in a tensioned condition continuously through a heat-setting zone, conically shaped rollers angularly arranged at opposite sides of said zone for separating said yarns from one another and withdrawing the separated yarns, and drive means for said rollers whereby any unbalance of tension as between the withdrawn yarns causes shifting of said yarns axially of said conically shaped rollers thereby automatically increasing the rate of withdrawal of one yarn and decreasing the rate of withdrawal of the other until said tensions are again balanced.

9. Apparatus for modifying heat-settable yarn filaments comprising means for feeding a plurality of yarns in a downstream direction in a twisted, tensioned condition, means forming a heat-setting zone downstream of said feed means, cooling means downstream of said heating means and proximate to the path of movement of the twisted yarn emerging from said heating zone for cooling the yarn in a twisted condition, and withdrawal means downstream of said cooling means for separating said yarns from one another while tensioned and simultaneously balancing the tensions of the withdrawal yarns when the tension of either is decreased relative to the other.

10. Apparatus for modifying heat-settable yarn filaments comprising separate feed means for feeding separate yarns, means for driving said feed means, mean-s downstream of said feed means forming an elongated twist zone in which said yarns are twisted together, heating means downstream of said feed means and in said twist zone for heating said yarn in a twisted, tensioned condition, a pair of separate withdrawal means downstream of said heating means and located at opposite sides of said elongated twist zone for separating said yarns from one another after heating while tensioned, means for driving said withdrawal means in timed relation to the drive of said feed means, thereby maintaining said twisted yarns under tension and maintaining a floating point of yarn separation at the downstream end of said twist zone, and automatic means for balancing the withdrawal tensions of said yarns.

11. The apparatus defined in claim 10 wherein at least one of said withdrawal means comprises a roll forming a nip for the yarn withdrawn, said roll having a substantially conical surface.

12. The apparatus defined in claim 11 wherein means are provided for adjusting the position of said roll relative to the position of said point of separation.

13. The apparatus defined in claim 10 wherein both said withdrawal means comprise substantially conical rolls forming nips for the respective yarns, and wherein pivot means are provided downstream of said twist zone and connected to said rolls for swinging movement of said rolls toward and away from one another.

14. The apparatus defined in claim 10, wherein return means are provided extending from one of said withdrawal means to one of said feed means for returning and refeeding one of the yarns withdrawn.

15. In a method of modifying thermoplastic heatsettable yarn filaments the steps which comprise pretwisting a plurality of ends of said yarns together, tensioning them, passing them while twisted through a heating zone maintained at a heat-setting temperature, cooling the heat-set yarns in a twisted, tensioned condition,

stantially constant tension on the twisted yarns.

new

other by withdrawing said yarns in different directions,

and automatically varying the withdrawal rates of said yarn ends relative to each other to thereby maintain sub:

16. Apparatus for modifying 'heat-settable yarn filaments comprising means for feeding a plurality of yarns in a downstream direction in a twisted, tensioned condition, means forming a heat-setting zone downstream of said feed means, and withdrawal means downstream-of said heat-setting zone for separating said yarns from one another while tensioned and simultaneously balancing the .8' tensions of the drawn yarns when the tension of either is decreased relative to the other.'

References Cited in the file of this patent UNITED STATES PATENTS 2,881,584 Billion Apr. 14, 1959 2,987,869 Klein June 13, 1961 a FOREIGN PATENTS 1,241,488 France Aug. 8, 1960 581,121 Italy Aug 20, 1958 

1. IN A METHOD OF MODIFYING THERMOPLASTIC HEAT-SETTABLE YARN FILAMENTS THE STEPS WHICH COMPRISE PRE-TWISTING A PLURALITY OF ENDS OF SAID YARNS TOGETHER, TENSIONING THEM, PASSING THEM WHILE TWISTED THROUGH A HEATING ZONE MAINTAINED AT A HEAT-SETTING TEMPERATURE, COOLING THE HEAT-SET YARNS IN A TWISTED, TENSIONED CONDITION, SEPARATING THE ENDS OF YARN CONTINUOUSLY FROM ONE ANOTHER BY WITHDRAWING SAID YARNS DIFFERENT DIRECTIONS, AND AUTOMATICALLY VARYING THE RATE OF WITHDRAWAL OF EACH YARN THEREBY MAINTAINING SUBSTANTIALLY CONSTANT TENSION ON THE TWISTED YARNS. 